The built environment plays an important role in tackling climate change. This industry is responsible for more greenhouse gas emissions than any other sector of the economy, contributing nearly 40% of annual CO2 emissions globally. That’s a significant figure, and one that needs urgent attention if we’re to keep global temperatures down to avoid the worst effects of climate change.

It’s an urgency that the sector is taking seriously. In 2018, the World Green Building Council officially launched the Net Zero Carbon Buildings Commitment, which sets out an ambitious vision. By 2050, all new buildings and renovations must have net zero embodied carbon, and all buildings – including existing buildings – must have net zero operational carbon (more on the difference between these two in a moment). The businesses and organisations signed up to the voluntary commitment now cover nearly 6,000 assets, over 32 million m2 of total floor area and $100 billion in annual turnover. This will add up to a saving of approximately 3.4 million tonnes of CO2 in 2030 alone.

Evidently, taking action in this area will make a positive and vital difference to climate change, but it also makes good business sense. Buildings are traditionally viewed as being at the edge of the grid – everything happens up stream and a building is at the end of the wire consuming kilowatt hours. This is why it’s so easy for developers and building operators to put the benefits of net zero into pounds and pence and returns on investment.

Net zero ambitions are also likely to dictate future planning and development legislation (and funding interest), and while the UK market is not yet consistently accounting for carbon intensity in property valuation, that is likely to change. The NABERS energy rating scheme in Australia, for example, is credited with halving the average energy intensity of commercial property and reducing the gap between the carbon emission profile of a building at design stage and its actual carbon emissions during performance. The driver? Commercial properties with a high NABERS rating come with an average premium of 20%, which doubles down on the business case for net zero.

Net zero in practice

So what needs to happen to get a building to net zero? First, we must consider the type of emissions we’re dealing with – the conversation around these two distinctive types has shifted in recent times.  

Firstly, there are operational emissions. These are the emissions created as a result of the building’s everyday use – such as heating, lighting, equipment and so on – and which are often dependent on the activities and decisions of the building occupants. Operational emissions have been the focus of carbon reduction activities for many years now, and building managers are increasingly aware of ways to mitigate these.

For new developments and buildings in the planning stages, however, there are embodied emissions – those that are associated with the materials and construction processes throughout the lifecycle of the building. This is a vast and sprawling area, covering everything from the emissions associated with the extraction of raw materials (such as sand for concrete), to emissions created in the manufacture of equipment and materials when a building needs repairs, to the emissions created when a building is eventually deconstructed or demolished. Embodied emissions represent the next big challenge for the built environment, as solutions in this area are not yet well defined.

Each type of emission has very different considerations. If you’re looking at achieving net zero in an existing building, for example, you’ll have very little control over its embodied emissions since it has already been built – and best practice is still being developed. Operational emissions are easier to manage, but retrofitting carbon reduction equipment and tech in existing buildings can present challenges you won’t get if you’re designing the building from scratch.

For operational emissions, it’s all about increasing energy efficiency, which is fairly straightforward as a concept. You want to do more with less, and there are lots of quick wins here, such as LED lighting, occupancy sensors, draught-proofing, insulation and proper heating and ventilation maintenance.

Managing embodied emissions is more of an unwieldy challenge, but one that at least affords the benefit of starting with a clean slate. Net zero targets need to be built into plans and designs that then be used to inform material choices. Cross-laminated timber, for example, is often mentioned as an alternative to more carbon-intensive building materials, but there are many others, including recycled concrete and concrete where a proportion of the mix is made from crushed plastic. Many carbon conscious developers will seek out local materials, or materials that can be repurposed, and the truly sustainable will even consider the building’s end of life – can it be disassembled so component parts can be used elsewhere?

Considering the whole life cycle

Indeed, while embodied and operational emissions are often considered separately, to get buildings to net zero we have to consider their entire life cycle, and in doing so we’ll see there’s a whole host of checks and balances involved. Does triple glazing save enough operational carbon to justify its embodied impact, for example? Can more intensive embodied carbon be justified if it will mitigate life-span risks such as floods? Looking at any one element solely in isolation will mean missed opportunities and minimal gains.

Underpinning these considerations are two things: teamwork and data. Making sure that everyone involved is on the same page is vital. Challenges come when different stakeholders are fragmented and don’t consider wider implications. There remains a focus on operational emissions, but embodied emissions demand equal attention and so the entire project must be considered holistically. Investors, designers, developers, constructors and operators can all bring valuable insight to the table, and their decisions are symbiotic, so the team needs to move as a whole.

Secondly, the importance of data can’t be underestimated. Whether it’s properly capturing data in the design process to help later with operational decisions, or gathering data regarding the routines of a building’s energy consumption, you can’t begin to reduce something unless you know what your baselines are.  

Ultimately, getting buildings to net zero – from the ground up or retroactively – is a journey. While the industry is making great headway, there’s still a lot to learn, so collaboration, partnerships and knowledge sharing will be critical if we’re to hit the ambitious climate targets necessary, and to create a viable, sustainable built environment that everyone can enjoy in the future.